Atoms in their elemental form

Oct 13, 2025 by wbrum.org 131 views

Understanding Oxidation Numbers

Oxidation numbers are a way to keep track of the number of electrons an atom has gained or lost in a compound. This concept is crucial in chemistry, as it helps us understand the properties and behavior of elements and compounds. In this article, we will focus on determining the oxidation number of nitrogen (N) in the compound ammonia (NH3).

The Rules for Assigning Oxidation Numbers

To assign oxidation numbers, we follow a set of rules:

Atoms in their elemental form have an oxidation number of 0. For example, oxygen (O2) has an oxidation number of 0.
Monatomic ions have an oxidation number equal to their charge. For example, sodium (Na+) has an oxidation number of +1.
Oxygen usually has an oxidation number of -2, except in peroxides where it is -1.
Hydrogen usually has an oxidation number of +1, except in hydrides where it is -1.
Fluorine always has an oxidation number of -1.
Chlorine usually has an oxidation number of -1, except in hypochlorous acid where it is +1.
Bromine usually has an oxidation number of -1, except in hypobromous acid where it is +1.
Iodine usually has an oxidation number of -1, except in hypoidous acid where it is +1.
Sulfur usually has an oxidation number of -2, except in sulfurous acid where it is +4 and in sulfuric acid where it is +6.
Nitrogen usually has an oxidation number of -3, except in nitric acid where it is +5.

Applying the Rules to NH3

Now that we have the rules, let's apply them to the compound NH3. We know that hydrogen (H) usually has an oxidation number of +1. Since there are three hydrogen atoms in NH3, the total oxidation number of hydrogen is 3(+1) = +3.

Determining the Oxidation Number of Nitrogen

To determine the oxidation number of nitrogen, we need to subtract the total oxidation number of hydrogen from the total charge of the compound. The total charge of NH3 is 0, since it is a neutral compound. Therefore, we can set up the equation:

Oxidation number of nitrogen + (+3) = 0

To solve for the oxidation number of nitrogen, we subtract +3 from both sides of the equation:

Oxidation number of nitrogen = -3

Conclusion

In conclusion, the oxidation number of nitrogen in the compound NH3 is -3. This is because the total oxidation number of hydrogen is +3, and the total charge of the compound is 0. Therefore, the oxidation number of nitrogen must be -3 to balance the equation.

Frequently Asked Questions

What is the oxidation number of hydrogen in NH3? The oxidation number of hydrogen in NH3 is +1.
What is the oxidation number of oxygen in NH3? The oxidation number of oxygen in NH3 is 0, since oxygen is not present in the compound.
What is the oxidation number of nitrogen in NH4+? The oxidation number of nitrogen in NH4+ is +3.

References

Atkins, P. W., & De Paula, J. (2010). Physical chemistry. Oxford University Press.
Brown, T. E., & LeMay, H. E. (2014). Chemistry: The Central Science. Pearson Education.
Petrucci, R. H., Harwood, W. S., & Herring, F. G. (2016). General chemistry: Principles and modern applications. Pearson Education.

Understanding Oxidation Numbers

Oxidation numbers are a fundamental concept in chemistry that helps us understand the properties and behavior of elements and compounds. In our previous article, we discussed the rules for assigning oxidation numbers and applied them to the compound NH3. In this article, we will answer some frequently asked questions about oxidation numbers.

Q&A

Q: What is the oxidation number of hydrogen in NH3?

A: The oxidation number of hydrogen in NH3 is +1.

Q: What is the oxidation number of oxygen in NH3?

A: The oxidation number of oxygen in NH3 is 0, since oxygen is not present in the compound.

Q: What is the oxidation number of nitrogen in NH4+?

A: The oxidation number of nitrogen in NH4+ is +3.

Q: What is the oxidation number of chlorine in HCl?

A: The oxidation number of chlorine in HCl is -1.

Q: What is the oxidation number of sodium in Na+?

A: The oxidation number of sodium in Na+ is +1.

Q: What is the oxidation number of oxygen in H2O?

A: The oxidation number of oxygen in H2O is -2.

Q: What is the oxidation number of sulfur in H2S?

A: The oxidation number of sulfur in H2S is -2.

Q: What is the oxidation number of nitrogen in NO3-?

A: The oxidation number of nitrogen in NO3- is +5.

Q: What is the oxidation number of oxygen in O2?

A: The oxidation number of oxygen in O2 is 0, since oxygen is in its elemental form.

Q: What is the oxidation number of hydrogen in H2O2?

A: The oxidation number of hydrogen in H2O2 is +1.

Q: What is the oxidation number of oxygen in H2O2?

A: The oxidation number of oxygen in H2O2 is -1.

Q: What is the oxidation number of sulfur in SO2?

A: The oxidation number of sulfur in SO2 is +4.

Q: What is the oxidation number of oxygen in SO2?

A: The oxidation number of oxygen in SO2 is -2.

Q: What is the oxidation number of nitrogen in N2O?

A: The oxidation number of nitrogen in N2O is +1.

Q: What is the oxidation number of oxygen in N2O?

A: The oxidation number of oxygen in N2O is -2.

Conclusion

In conclusion, oxidation numbers are a crucial concept in chemistry that helps us understand the properties and behavior of elements and compounds. By applying the rules for assigning oxidation numbers, we can determine the oxidation number of any element in a compound. We hope that this article has helped you understand oxidation numbers better and has answered some of your frequently asked questions.

Frequently Asked Questions: Oxidation Numbers

What is the oxidation number of an atom in its elemental form? The oxidation number of an atom in its elemental form is 0.
What is the oxidation number of a monatomic ion? The oxidation number of a monatomic ion is equal to its charge.
What is the oxidation number of oxygen in a peroxide? The oxidation number of oxygen in a peroxide is -1.
What is the oxidation number of hydrogen in a hydride? The oxidation number of hydrogen in a hydride is -1.

References

Atkins, P. W., & De Paula, J. (2010). Physical chemistry. Oxford University Press.
Brown, T. E., & LeMay, H. E. (2014). Chemistry: The Central Science. Pearson Education.
Petrucci, R. H., Harwood, W. S., & Herring, F. G. (2016). General chemistry: Principles and modern applications. Pearson Education.